yodamutt89

hey guys im new to trucks so dont laugh at me but i bought a 89 pickup with a 350 smallblcock. well lastnight the charge light stated coming on i work at advance auto so i tested the alternator turned out to be good. so i dont know if i have a harness going bad but i wanted to put the gm alternator on anyway if the harness is good im using a 2 wire gm 78 amp alternator for it i got the plug for it here on the counter it has a red wire and a white wire on it. im wondering what wires i need to splice into on the factory 3 plug harness from toyota to make this work. the wires are red green and yellow i believe. any help would be great thank you.